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The ‘Big One:’ How could it affect the Central Coast?


It’s been more than 100 years since the 1906 earthquake that caused severe damage to San Francisco. Since then, Californians have long-anticipated another ‘Big One’ to hit along the San Andreas Fault. 

Based on seismic history and current data on the earthquake cycle, it’s widely anticipated that the next ‘Big One’ will hit Southern California.

According to Cal Poly geology professor John Jasbinsek, since earthquakes do not follow a strict cycle, it’s difficult to predict when exactly an earthquake may hit.

Jabinsek said paleo-seismologists have hypothesized that the next ‘Big One’ along the San Andreas Fault will have a magnitude of around 7 or 7.5, which is slightly less than the 1906 San Francisco earthquake’s magnitude of 7.9.

“It would still be a devastating event, in the southern part of the San Andreas fault,” Jasbinsek said.

Of course, local damage would depend on the epicenter of the earthquake. If an earthquake occurs in the Bay Area, impacts to the Central Coast would be smaller, but if it happens in the Central Valley, impacts could be much larger.

In terms of the potential damage of this hypothetical earthquake, Cal Poly geotechnical engineering professor Rob Moss said ground damage, liquefaction and disruption of electricity are among the potential effects of such a large earthquake.

Liquefaction refers to solid ground becoming more liquid due to stress from ground accelerations during an earthquake.

According to Moss, the Central Coast and California overall have strict building codes that are meant to prevent collapses during an earthquake.

“In California, we have the best building codes in the world. And it's, it's twofold. You have to have building codes, and you have to have enforcement,” Moss said. “And so that's part of the preparedness, it's, it's long term planning, good building codes, good enforcement, and then personal responsibility and thinking about.”

Beside building codes, San Luis Obispo County has an emergency plan in place.

But, San Luis Obispo County Emergency Services Manager Scott Jalbert said it would take roughly 72 hours for regional, federal and state assistance to arrive after an earthquake.

“??But probably the more important thing is that the citizens need to know that they may be on their own for up to three days and they need to be prepared,” Jalbert said.

Other measures the county has taken to prepare include identifying target hazards, key infrastructure and making sure that hospitals have back-up generators.

Cal Poly also has its own Emergency Management Director, Anthony Knight, who is in charge of planning, preparation, outreach and response for all hazards that might affect the campus community.

“We need to do risk assessments and hazard vulnerability assessments to determine what our threats are here at Cal Poly, one of those being an earthquake,” Knight said. “In California, it’s one of our major seasons – fire, flood, wind and earthquakes.”

Cal Poly has its own emergency operations plan, and preparation measures and information can also be found online at

Knight advises being prepared by storing water and food as earthquakes can disrupt power and water lines.

To prepare an earthquake emergency kit, visit San Luis Obispo County’s preparedness website.

Editor's note: An earlier version of this story stated that the San Andreas Fault does not run through San Luis Obispo County. In fact, it does run through the northeast section of the county.

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